FENS Forum 2006

For lectures, symposia and workshops, time indicates the beginning of the session.
For posters, authors are expected to be in attendance at their posters at the time indicated.

First author: Ganeshina, Olga (poster)

Poster board 28 - Sun 09/07, 16:00 - Hall X
Session 038 - Sensory systems: auditory I
Abstract A038.6, published in FENS Forum Abstracts, vol. 3, 2006.
Ref.: FENS Abstr., vol.3, A038.6, 2006

Author(s) Ganeshina O. (1), Kuznetsov S. A. (2) & Vorobyev M. (1)

Addresse(s) (1) VTHRC, SBMS, Universiy of Queensland, Brisbane, Australia; (2) Inst. Cell. Biol. Biosys. Tech., University of Rostock, Rostock, Germany

Title Vimentin-based cytoskeleton in contractile cells of the cochlear frame in geckos.

Text Previously we described a contractile muscle-like tissue within the cartilaginous cochlear frame in the gecko Teratoscincus scincus. Electron microscopy has revealed that the contractile cells are densely packed with 7-10 nm thick filaments, homogeneously distributed within the cytoplasm. We suggested that contractility of this tissue could be mediated by an acto-myosin system and may serve as a mechanism of slow mechanical adaptation in the gecko cochlea. Here we demonstrate, that the cochleae of two other gecko species, Gecko gekko and Eublepharis macularis, also possess the muscle-like tissue, which exhibits contractile properties. Motile response of the permeabilized tissue in response to 20 mM ATP was demonstrated using a steady-flow chamber. Surprisingly, specific staining of actin filaments with rhodamine-phalloidin showed distinct fluorescence labeling only in a thin layer beneath the cell membrane in the contractile cells. The rest of the cytoplasm containing the densely packed 7-10 nm filaments exhibited only background levels of fluorescence. In contrast, hair cell stereocilia used as a positive control, showed strong labeling. SDS-gel electrophoresis of isolated contractile tissue revealed a major protein component of about 57 kDa. A band of 42 kDa, characteristic for actin, represented a minor component. The 57 kDa protein has been identified using nanoLC-ESI-MS/MS technique. The protein shows homology with the intermediate filament protein, vimentin, of the snake Daboia russellii (p<0.05). Our data indicate that the contractile cells within the cochlear frame are equipped with an unusually arranged cytoskeleton composed of tightly packed intermediate filaments enriched with vimentin. Further studies are needed to find out whether the properties of the contractile tissue are consistent with an ability to effectively modulate macro-mechanics of the gecko cochlea.

Theme Sensory systems
Auditory / Peripheral

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Author(s)	Ganeshina O. (1), Kuznetsov S. A. (2) & Vorobyev M. (1)
Addresse(s)	(1) VTHRC, SBMS, Universiy of Queensland, Brisbane, Australia; (2) Inst. Cell. Biol. Biosys. Tech., University of Rostock, Rostock, Germany
Title	Vimentin-based cytoskeleton in contractile cells of the cochlear frame in geckos.
Text	Previously we described a contractile muscle-like tissue within the cartilaginous cochlear frame in the gecko Teratoscincus scincus. Electron microscopy has revealed that the contractile cells are densely packed with 7-10 nm thick filaments, homogeneously distributed within the cytoplasm. We suggested that contractility of this tissue could be mediated by an acto-myosin system and may serve as a mechanism of slow mechanical adaptation in the gecko cochlea. Here we demonstrate, that the cochleae of two other gecko species, Gecko gekko and Eublepharis macularis, also possess the muscle-like tissue, which exhibits contractile properties. Motile response of the permeabilized tissue in response to 20 mM ATP was demonstrated using a steady-flow chamber. Surprisingly, specific staining of actin filaments with rhodamine-phalloidin showed distinct fluorescence labeling only in a thin layer beneath the cell membrane in the contractile cells. The rest of the cytoplasm containing the densely packed 7-10 nm filaments exhibited only background levels of fluorescence. In contrast, hair cell stereocilia used as a positive control, showed strong labeling. SDS-gel electrophoresis of isolated contractile tissue revealed a major protein component of about 57 kDa. A band of 42 kDa, characteristic for actin, represented a minor component. The 57 kDa protein has been identified using nanoLC-ESI-MS/MS technique. The protein shows homology with the intermediate filament protein, vimentin, of the snake Daboia russellii (p<0.05). Our data indicate that the contractile cells within the cochlear frame are equipped with an unusually arranged cytoskeleton composed of tightly packed intermediate filaments enriched with vimentin. Further studies are needed to find out whether the properties of the contractile tissue are consistent with an ability to effectively modulate macro-mechanics of the gecko cochlea.
Theme	Sensory systems Auditory / Peripheral